In recent years, operative procedures such as endoscopic submucosal dissection (ESD) have come to be used, where ESD involves inserting a treatment instrument through the mouth or anus and removing one slice from an upper layer of a mucous membrane over a wide area of the stomach or large intestine without penetrating stomach or large-intestine walls. Furthermore, an operative procedure (NOTES: Natural Orifice Translumenal Endoscopic Surgery) is known which involves inserting a flexible endoscope such as an upper or lower gastrointestinal endoscope through the mouth, anus, vagina, or urethra which originally exists in the surface of the body, then taking the flexible endoscope to an abdominal cavity by penetrating a stomach or large-intestine wall, and conducting diagnosis or treatment on an abdominal organ.
Since the natural orifice translumenal endoscopic surgery typified by endoscopic submucosal dissection (ESD) conducts treatment or the like by inserting a treatment instrument such as forceps or a scalpel together with a flexible endoscope through the mouth or the like which originally exists in the surface of the body, and taking the treatment instrument to a diseased part, the surgery causes no damage to the surface of the body, can eliminate complications such as infection or adhesion of the abdominal wall, which accompany ordinary surgery, and can reduce stress on the human body.
As described in Patent Literature 1, the treatment instrument used for the natural orifice translumenal endoscopic surgery includes a bending portion inserted into the flexible endoscope and used to bendably manipulate the treatment instrument projecting from a distal end of the flexible endoscope. Also, the treatment instrument includes a sheath and wire unit adapted to transmit bending motion to the bending portion and an operating portion used to manipulate the bending motion of the bending portion by pushing and pulling the sheath and wire.
Also, regarding a configuration of the operating portion, a structure is known in which a control member having at least two degrees of freedom is attached to a rail and multiple degrees of freedom are given to a treatment instrument.